Eulerian simulation of the fluid dynamics of helicopter brownout

C. Phillips, R.E. Brown

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

A computational model is presented that can be used to simulate the development of the dust cloud that can be entrained into the air when a helicopter is operated close to the ground in desert or dusty conditions. The physics of this problem, and the associated pathological condition known as 'brownout' where the pilot loses situational awareness as a result of his vision being occluded by dust suspended in the flow around the helicopter, is acknowledged to be very complex. The approach advocated here involves an approximation to the full dynamics of the coupled particulate-air system. Away from the ground, the model assumes that the suspended particles remain in near equilibrium under the action of aerodynamic forces. Close to the ground, this model is replaced by an algebraic sublayer model for the saltation and entrainment process. The origin of the model in the statistical mechanics of a distribution of particles governed by aerodynamic forces allows the validity of the method to be evaluated in context by comparing the physical properties of the suspended particulates to the local properties of the flow field surrounding the helicopter. The model applies in the Eulerian frame of reference of most conventional Computational Fluid Dynamics codes and has been coupled with Brown's Vorticity Transport Model. Verification of the predictions of the coupled model against experimental data for particulate entrainment and transport in the flow around a model rotor are encouraging. An application of the coupled model to analyzing the differences in the geometry and extent of the dust clouds that are produced by single main rotor and tandem-rotor configurations as they decelerate to land has shown that the location of the ground vortex and the size of any regions of recirculatory flow, should they exist, play a primary role in governing the extent of the dust cloud that is created by the helicopter.
LanguageEnglish
Pages1416-1429
Number of pages14
JournalJournal of Aircraft
Volume46
Issue number4
DOIs
Publication statusPublished - Jul 2009
Event64th American Helicopter Society Annual Forum - Montréal, Canada
Duration: 28 Apr 20081 May 2008

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Fluid dynamics
Helicopters
Dust
Rotors
Aerodynamics
Statistical mechanics
Air
Vorticity
Flow fields
Computational fluid dynamics
Vortex flow
Physics
Physical properties
Geometry

Keywords

  • eulerian simulation
  • fluid dynamics
  • helicopter brownout
  • aerodynamic forces
  • vorticity transport model

Cite this

Phillips, C. ; Brown, R.E. / Eulerian simulation of the fluid dynamics of helicopter brownout. In: Journal of Aircraft. 2009 ; Vol. 46, No. 4. pp. 1416-1429.
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Eulerian simulation of the fluid dynamics of helicopter brownout. / Phillips, C.; Brown, R.E.

In: Journal of Aircraft, Vol. 46, No. 4, 07.2009, p. 1416-1429.

Research output: Contribution to journalArticle

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